Power transmitting and receiving apparatus and method for performing a wireless multi-power transmission

ABSTRACT

A method and an apparatus for wireless power transmission by a power transmitting apparatus is provided. The method includes transmitting detection power towards a power receiving apparatus, detecting an impedance change made by the power receiving apparatus, transmitting driving power for communication with the power receiving apparatus towards the power receiving apparatus, receiving a search signal from the power receiving apparatus within a preset time, and determining whether the impedance change is within a first acceptable range based on the received search signal.

PRIORITY

This application is a Continuation Application of, and claims priorityunder 35 U.S.C. § 120 to, U.S. patent application Ser. No. 13/474,338filed in the U.S. Patent and Trademark Office on May 17, 2012, whichclaims priority under 35 U.S.C. § 119(a) to Korean Patent ApplicationSerial Nos. 10-2011-0046445 and 10-2012-0051506, which were filed in theKorean Intellectual Property Office on May 17, 2011 and May 15, 2012,respectively, the entire content of each of which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a method and an apparatus fortransmitting and receiving power, and more particularly, to a method andan apparatus for performing wireless multi-power transmissions between aplurality of power receiving apparatuses and a power transmittingapparatus.

2. Description of the Related Art

A conventional power transmitting apparatus and power receivingapparatus perform an initial setup for wireless power transmission, andthereafter, power transmission and reception is performed between thepower transmitting apparatus and power receiving apparatus havingcompleted the initial setup.

In general, to perform wireless power charging, a power receivingapparatus performs an authentication with a power transmittingapparatus, and upon successful authentication, receives wireless powerfrom the power transmitting apparatus. When the charging is completed,the power receiving apparatus transmits a charging completion message tothe power transmitting apparatus, indicating that the charging iscompleted. Upon receiving the charging completion message, the powertransmitting apparatus stops transmitting power to the power receivingapparatus.

Thereafter, the power transmitting apparatus transmits a rechargingidentification message, which identifies whether the power receivingapparatus performs recharging, to the power receiving apparatus, basedon a regular time interval.

Upon receiving the recharging identification message, the powerreceiving apparatus generates a recharging request message forrequesting recharging, if recharging is needed, and transmits thegenerated recharging request message to the power transmittingapparatus. Thereafter, the power receiving apparatus receives wirelesspower for charging from the power transmitting apparatus.

If recharging is not needed, the power receiving apparatus may ignorethe received recharging identification message or transmit a rechargingrejection message, which indicates that the power receiving apparatusdoes not want to perform recharging.

However, the above-described convention procedure is problematic whenthe wireless power transmission is performed between the powertransmitting apparatus and multiple power receiving apparatuses, as itdoes not take into account conditions of power receiving apparatuses orresource limitations of the power transmitting apparatus, e.g., whetherthe power transmitting apparatus can perform the wireless powertransmission with each of the multiple power receiving apparatuses, nordoes it provide a protocol for when the power transmitting apparatuscannot perform the wireless power transmission with each of the multiplepower receiving apparatuses.

SUMMARY OF THE INVENTION

The present invention is designed to address at least the problemsand/or disadvantages described above and to provide at least theadvantages described below.

Accordingly, an aspect of the present invention is to provide anapparatus and a method for performing wireless power transmission with aplurality of power receiving apparatuses in consideration of conditionsof the plurality of power receiving apparatuses.

In accordance with an aspect of the present invention, a method forwireless power transmission by a power transmitting apparatus isprovided. The method includes transmitting detection power towards apower receiving apparatus, detecting an impedance change made by thepower receiving apparatus, transmitting driving power for communicationwith the power receiving apparatus towards the power receivingapparatus, receiving a search signal from the power receiving apparatuswithin a preset time, and determining whether the impedance change iswithin a first acceptable range based on the received search signal.

In accordance with another aspect of the present invention, a powertransmitting apparatus for wireless power transmission is provided. Thepower transmitting apparatus includes a resonator, a communication unit,and a controller. The controller is configured to at least control totransmit detection power through the resonator towards a power receivingapparatus, detect an impedance change made by the power receivingapparatus, transmit driving power for communication with the powerreceiving apparatus, through the resonator, towards the power receivingapparatus, receive a search signal from the power receiving apparatuswithin a preset time, through the communication unit, determine whetherthe impedance change is within a first acceptable range based on thesearch signal, and transmit an approval message towards the powerreceiving apparatus, through the communication unit, based on theimpedance change being within the acceptable range.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present invention will be more apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a block diagram illustrating a power transmitting apparatusaccording to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating a power receiving apparatusaccording to an embodiment of the present invention;

FIGS. 3 to 5 are flowcharts illustrating a process in which a powertransmitting apparatus manages a plurality of power receivingapparatuses in performing wireless power transmission according to anembodiment of the present invention;

FIGS. 6 to 7 are flowcharts illustrating a process in which a powerreceiving apparatus performs wireless power transmission with a powertransmitting apparatus according to an embodiment of the presentinvention;

FIG. 8 is a diagram illustrating states of a power receiving apparatusaccording to an embodiment of the present invention; and

FIG. 9 illustrates an example of a power receiving apparatus managementtable according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will now be described indetail with reference to the accompanying drawings. In the followingdescription, specific details such as detailed configuration andcomponents are merely provided to assist the overall understanding ofthese embodiments of the present invention. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein can be made withoutdeparting from the scope and spirit of the present invention. Inaddition, descriptions of well-known functions and constructions areomitted for clarity and conciseness.

According to an embodiment of the present invention, a powertransmitting apparatus can stably supply power to a plurality of powerreceiving apparatuses by determining power transmission states of theplurality of power receiving apparatuses.

Embodiments of the present invention will be described below, wherein anew power receiving apparatus desires to participate in a network whilethe power transmitting apparatus is performing wireless powertransmission with a plurality of power receiving apparatuses.

FIG. 1 is a block diagram illustrating a power transmitting apparatusaccording to an embodiment of the present invention.

Referring to FIG. 1, the power transmitting apparatus 100 includes apower supplier 110, a controller 120, an amplification unit 130, aresonator 140, a communication unit 150, and a measurement unit 160.

The power supplier 110 generates power based on a power transmissioncontrol value provided by the controller 120.

The controller 120 may include a Central Processing Unit (CPU), a ReadOnly Memory (ROM) storing a control program for controlling the powertransmitting apparatus, and a Random Access Memory (RAM), which stores asignal or data input from an outside of the power transmittingapparatus. Here, the CPU may include a single core, a dual core, atriple core, or a quad core. The CPU, the ROM, and the RAM can beconnected with each other through an internal bus. Here, the controller120 may be referred to as a Main Control Unit (MCU).

The controller 120 controls the power supplier 110, the amplificationunit 130, the resonator 140, the communication unit 150, and themeasurement unit 160. Particularly, the controller 120 detects the powerreceiving apparatus 200 and determines whether the detected powerreceiving apparatus 200 is located in an effective position suitable forreceiving wireless power. When the power receiving apparatus 200 islocated in the effective position, the controller 120 transmits wirelesspower for communication to the power receiving apparatus 200. Forexample, the controller 120 can detect the power receiving apparatus 200through a change in a load value detected by the resonator 140. Thecontroller 230 calculates a changed load value, and determines that thepower receiving apparatus 200 is located in the effective position whenthe calculated changed load value is larger than a preset threshold andthen stores the calculated changed load value.

The controller 120 determines whether a network subscription requestmessage for subscribing to a wireless multi-power transmission networkis received from the power receiving apparatus 200 within a preset time.For example, the network subscription request message includes anIDentifier (ID), a protocol version, and a reference load value of thepower receiving apparatus 200.

If the network subscription request message is received within thepreset time, the controller 120 compares the reference load valuecontained in the network subscription request message with the changedload value and determines whether the changed load value is within anacceptable range. Here, the controller 120 determines whether thechanged load value is within the acceptable range by using a referenceload value from the power receiving apparatus 200. That is, thecontroller 120 determines whether the stored reference load value iswithin the acceptable range based on the changed load value according tothe reference load value of the power receiving apparatus 200.

If the changed load value is within the acceptable range, the controller120 determines whether the power receiving apparatus 200 havingrequested a subscription to the network is permitted to subscribe to thewireless multi-power transmission network. Here, the wirelessmulti-power transmission network refers to a network configured by onetransmitting apparatus and a plurality of power receiving apparatuses inorder to exchange information for the wireless power transmission.

For example, when the power receiving apparatus 200 has a reference loadvalue of 10Ω, it is assumed that a current increased by 100 mA ismeasured in the resonator 140 when the power supplier 110 applies avoltage of 12 V. A changed load value may be 100 mA. Thereafter, when achanged load value is measured in the resonator 140 through themeasurement unit 160, the controller 120 determines whether the measuredchanged load value is within a margin of error of 10%. If the measuredchanged load value is within the margin of error of 10%, the controller120 may determine that there is the power receiving apparatus 200 withthe reference load value of 10Ω. Otherwise, the controller 120 maydetermine that there are invalid materials.

If the changed load value of the power receiving apparatus 200 exceedsthe acceptable range, the controller 120 determines the power receivingapparatus 200 as a non-target apparatus for power, to which the powertransmitting apparatus does not transmit power, i.e., invalid materials.The invalid materials refer to other materials for receiving power,which are not the power receiving apparatus 200 to which the powertransmitting apparatus 100 desires to transmit wireless power. Suchinvalid materials include a metal material, an electronic device thatdoes not perform communication with the power transmitting apparatus100, and a power receiving apparatus 200 to which the power transmittingapparatus does not transmit the wireless power.

Further, when the network subscription request message is not receivedfrom the power receiving apparatus 200 within the preset time, thecontroller 120 identifies the power receiving apparatus 200 as theinvalid materials. Thereafter, the controller 120 stops transmitting thepower to the power receiving apparatus 200 determined as the non-targetapparatus for power.

The controller 120 determines whether the power receiving apparatus 200having requested the subscription to the wireless multi-powertransmission network can subscribe to the wireless multi-powertransmission network. If the power receiving apparatus can subscribe tothe wireless multi-power transmission network, the controller 120transmits a network subscription approval message to the power receivingapparatus 200. If the power receiving apparatus 200 cannot subscribe tothe wireless multi-power transmission network, the controller 120transmits a network subscription rejection message to the powerreceiving apparatus and stops transmitting the wireless power suppliedfor communication. When a number of power receiving apparatuses inexcess of an acceptable number subscribe to the wireless multi-powertransmission network or a protocol version of the power receivingapparatus 200 is higher than a protocol version of the wirelessmulti-power transmission network, the controller 120 can determine thatthe power receiving apparatus 200 cannot subscribe to the wirelessmulti-power transmission network.

For example, the network subscription approval message includescommunication information used for communication such as a network ID,schedule information, etc. Here, the network ID refers to an inherent IDof the power receiving apparatus 200 within the network used foridentifying a plurality of power receiving apparatuses in the wirelessmulti-power transmission network according to an embodiment of thepresent invention. The schedule information refers to information forcommunication in the wireless multi-power transmission network. Further,the network ID may include a session ID.

The controller 120 determines whether a power transmission requestmessage is received from the power receiving apparatus 200 within apreset time. When the power transmission request message is received,the controller 120 determines whether the power can be transmitted tothe power receiving apparatus 200. Specifically, the controller 120calculates a power value required by the power receiving apparatus 200by using a reference voltage, a reference current, and a referenceefficiency value of the power receiving apparatus 200 included in thepower transmission request message. Thereafter, the controller 120determines whether a value generated by adding the power value, which ismeasured by the measurement unit 160, being transmitted by the powertransmitting apparatus 100 and the calculated power value required bythe power receiving apparatus 200 is smaller than a maximum output powervalue of the power transmitting apparatus 100. The maximum output powervalue of the power transmitting apparatus 100 is a preset value.

If the value generated by adding the power value being transmitted bythe power transmitting apparatus 100 and the power value required by thepower receiving apparatus 200 is smaller than the maximum output powervalue of the power transmitting apparatus 100, the controller 120 candetermine that the power can be transmitted to the power receivingapparatus 200.

If the power transmission request message is not received, thecontroller 120 determines that there is no power receiving apparatus 200and stops transmitting the wireless power supplied for thecommunication.

Further, when it is determined that the power can be transmitted to thepower receiving apparatus 200, the controller 120 transmits a powertransmission approval message to the power receiving apparatus 200 andthen transmits the requested power to the power receiving apparatus 200.When it is determined that the power cannot be transmitted to the powerreceiving apparatus 200, the controller 120 transmits a powertransmission rejection message to the power receiving apparatus 200 andthen stops transmitting the wireless power supplied for thecommunication.

The controller 120 determines whether a power transmission state messageis received from the power receiving apparatus 200 within a preset time.If the power transmission state message is received, the controller 120stores values for a reception voltage, a reception current, an outputvoltage, and an output current of the power receiving apparatus 200included in the power transmission state message in a memory. If thepower transmission state message is not received within the preset time,the controller 120 determines that there is no power receiving apparatusand stops transmitting the wireless power supplied for thecommunication.

The controller 120 renews a power receiving apparatus management tablestored in a memory (not shown) by using the power transmission statemessage received from a plurality of power receiving apparatuses havingsubscribed to the wireless multi-power transmission network within thepreset time. The power receiving apparatus management table will bediscussed in more detail below.

The controller 120 can configure power transmission state information onthe plurality of power receiving apparatuses having subscribed to thewireless multi-power transmission network in the power receivingapparatus management table and store the configured power receivingapparatus management table in the memory, thereby managing the pluralityof power receiving apparatuses. For example, the power transmissionstate information on the plurality of power receiving apparatusesincludes a session ID set by each power receiving apparatus forcommunication with the power transmitting apparatus, and an ID, areference load, a reference current, a reference voltage, a referenceefficiency, a power transmission state, an input voltage, an inputcurrent, an output voltage, an output current, a transmission order, anda priority of each power receiving apparatus. The controller 120 managespower transmission to the plurality of power receiving apparatuses usingthe power receiving apparatus management table.

The controller 120 calculates a transmission power value, which thepower transmitting apparatus 100 desires to transmit to each powerreceiving apparatus, by using the power transmission state informationin the renewed power receiving apparatus management table.

The controller 120 calculates a leakage power value using an outputcurrent value, an output voltage value, a transmission power value, anda reference efficiency value of the power receiving apparatus 200received from the power receiving apparatus 200.

If the calculated leakage power value is within an acceptable range, thecontroller 120 changes a current transmission power value into thecalculated transmission power value and then transmits the changedcalculated transmission power value. If the calculated leakage powervalue is within a preset threshold, it is determined that the calculatedleakage power value is within the acceptable range. If the calculatedleakage power value exceeds the acceptable range, the controller 120determines the power receiving apparatus 200 as being the invalidmaterials and stops transmitting power. Thereafter, the controller 120changes the power transmission value according to the power transmissionstate message of the power receiving apparatus 200, until a powertransmission completion message is received from the power receivingapparatus 200, so as to continuously perform the wireless powertransmission.

When the power transmission completion message is received from thepower receiving apparatus, the controller 120 changes a currenttransmission power value into a power value used by the power receivingapparatus 200 for communication and then transmits the changed powervalue. For example, in accordance with an embodiment of the presentinvention, a transmission power value transmitted to a first powerreceiving apparatus is 3 W, a transmission power value transmitted to asecond power receiving apparatus is 4 W, and a power value used by thefirst power receiving apparatus and the second power receiving apparatusfor communication, respectively is 0.1 W. If power transmission to thefirst power receiving apparatus is completed, the controller 120transmits the power value of 0.1 W to the first power receivingapparatus and transmits the power value of 4 W to the second powerreceiving apparatus.

The amplification unit 130 increases the power generated by the powersupplier 110 and outputs the increased power. The amplification unit 130includes an amplifier.

The resonator 140 transmits the power in a resonant frequency, which iscontrolled under a control of the controller 120 according to the powergenerated from the amplification unit 130, to the power receivingapparatus 200. For example, the resonator 140 includes a coil or anantenna.

The communication unit 150 performs communication with one or more powerreceiving apparatuses, which are targets of the charging, and may useany type of wireless short-distance communication scheme. For example,the communication unit 150 includes a communication Integrated Circuit(IC).

The measurement unit 160 measures the power generated from the powersupplier 110 and transfers a transmission power value of the powertransmitting apparatus 100 to the controller 110.

As described above, the power transmitting apparatus according to anembodiment of the present invention can stably transmit power to eachpower receiving apparatus by considering power transmission states of aplurality of power receiving apparatuses.

FIG. 2 is a block diagram illustrating a power receiving apparatusaccording to embodiments of the present invention.

Referring to FIG. 2, the power receiving apparatus 200 includes acontroller 210, a resonator 220, a rectification unit 230, a regulationunit 240, a battery unit 250, a communication unit 260, a firstmeasurement unit 270, and a second measurement unit 280.

The controller 210 controls operations of the resonator 220, therectification unit 230, the regulation unit 240, the battery unit 250,and the communication unit 260. Particularly, when power is received,the controller 210 generates the network subscription request messageincluding the ID, the protocol version, and the reference load value ofthe power receiving apparatus 200 and then transmits the generatednetwork subscription request message to the power transmitting apparatusfor the subscription to the wireless multi-power transmission network.Here, the ID of the power receiving apparatus can be used fordetermining a specification of the power receiving apparatus as well asidentifying the power receiving apparatus. Further, the protocol versionis used for grasping if communication is possible in the wirelessmulti-power transmission network, and the reference load value is usedfor detecting invalid materials or identifying a location of the powerreceiving apparatus 200, etc.

The controller 210 determines whether the network subscription approvalmessage is received from the power transmitting apparatus within thepreset time. When the network subscription approval message is received,the controller 210 transmits the power transmission request message forreceiving wireless power from the power transmitting apparatus to thepower transmitting apparatus.

If the network subscription rejection message is received from the powertransmitting apparatus within the preset time or no message is received,the controller 210 retransmits the network subscription request messageto the power transmitting apparatus.

Thereafter, the controller 210 determines whether the power transmissionapproval message is received from the power transmitting apparatuswithin the preset time. When the power transmission approval message isreceived, the controller 210 supplies power to the battery unit 250 byturning on a switch of an output terminal and measures a receptionvoltage, a reception current, an output voltage, and an output currentof the output terminal. Here, the output terminal is located between theregulation unit 240 and the battery unit 250.

The controller 210 generates the power transmission state messageincluding the measured output voltage, output current, measuredreception voltage, and reception current, and periodically transmits thegenerated power transmission state message to the power transmittingapparatus.

If the power transmission approval message is not received within thepreset time or the power transmission rejection message is received fromthe power transmitting apparatus, the controller 210 enters a powerreception standby state. That is, the controller 210 supplies power tothe battery unit 250 by turning on the switch of the output terminal andstops transmitting the power to the battery unit 250 after measuring theoutput voltage and the output current of the output terminal in thepower reception standby state. Subsequently, the controller 210transmits a power transmission standby state message including themeasured output voltage and output current to the power transmittingapparatus.

When the power reception is completed, the controller 210 stopssupplying power to the battery unit 250 by turning off the switch of theoutput terminal, generates the power transmission completion message forindicating that power transmission has been completed, and thentransmits the generated power transmission completion message to thepower transmitting apparatus. Thereafter, the controller 210 enters thepower reception standby state.

The controller supplies power to the battery unit by turning on theswitch of the output terminal and stops transmitting the power to thebattery unit after measuring the output voltage and the output currentof the output terminal in the power reception standby state. Thereafter,the controller 210 transmits the power transmission standby statemessage including the measured output voltage and output current to thepower transmitting apparatus.

The controller 210 determines whether the power reception is completed.If the power reception is completed, the controller 210 periodicallytransmits the power transmission standby state message to the powertransmitting apparatus and maintains a communication connection with thepower transmitting apparatus. If the power reception is not completed,controller 210 waits for receiving the power transmission approvalmessage during the preset time.

The resonator 220 receives wireless power from the resonator 140 of thepower transmitting apparatus and then outputs the received wirelesspower. The wireless power refers to an Alternating Current (AC) powersignal. For example, the resonator 220 includes a coil or an antenna.

The rectification unit 230 converts the received AC power signal to aDirect Current (DC) power signal. The rectification unit 230 includes arectifier.

The regulation unit 240 regulates a power amount charged to the batteryunit 250 for continuously maintaining a value set in the controller 210.The regulation unit 240 includes a regulator.

The battery unit 250 stores the wireless power regulated by theregulation unit 240. In accordance with different embodiments of thepresent invention, the battery unit 250 may be a battery unit of adevice equipped with the power receiving apparatus 200 or may bereplaced with the device equipped with the power receiving apparatus200. The battery unit 250 includes a battery.

The communication unit 260 performs communication with the powertransmitting apparatus. Accordingly, the communication unit 260 uses anysuitable type of wireless short-distance communication scheme. Thecommunication unit 260 includes a communication IC.

The first measurement unit 270 measures voltage or current informationrectified through the rectification unit 230, and the second measurementunit 280 measures voltage or current information input to the batteryunit 250.

As described above, a power transmitting apparatus according to anembodiment of the present invention, can stably transmit power to eachpower receiving apparatus by considering power transmission states of aplurality of power receiving apparatuses.

FIGS. 3 to 5 are flowcharts illustrating a process in which a powertransmitting apparatus manages a plurality of power receivingapparatuses in performing wireless power transmission according to anembodiment of the present invention.

Referring to FIG. 3, the controller 120 detects loads of the resonator140 and calculates the changed load value in step 300. Specifically, thecontroller 120 detects the power receiving apparatus 200 through thechanged load value detected by the resonator 140.

In step 301, the controller 120 determines whether the calculatedchanged load value is larger than a preset threshold. When thecalculated changed load value is larger than the preset threshold, thecontroller 120 transmits power for communication with the powerreceiving apparatus 200 to the power receiving apparatus 200 in step302.

However, when the calculated changed load value is not larger than thepreset threshold, step 300 is performed again, and thus, the changedload value is calculated and stored.

In step 303, the controller 120 determines whether a networksubscription request message for the subscription to the wirelessmulti-power transmission network is received from the power receivingapparatus 200 within the preset time. If the network subscriptionrequest message is received within the preset time, the controller 120compares the reference load value contained in the network subscriptionrequest message with the changed load value in step 304.

However, if the network subscription request message is not receivedwithin the preset time, the controller 120 determines the detected powerreceiving apparatus as invalid materials in step 309.

In step 305, the controller 120 determines whether the changed loadvalue is within an acceptable range.

When the reference load value is not within the acceptable range, thedetected power receiving apparatus is determined as the invalidmaterials in step 309.

When the reference load value is within the acceptable range, thecontroller 120 determines whether the power receiving apparatus cansubscribe to the wireless multi-power transmission network in step 306.

If the power receiving apparatus can subscribe to the wirelessmulti-power transmission network, the controller 120 transmits thenetwork subscription approval message to the power receiving apparatusin step 308.

If the power receiving apparatus cannot subscribe to the wirelessmulti-power transmission network in step 303, the controller 120transmits the network subscription rejection message to the powerreceiving apparatus in step 307. Referring to FIG. 5, the controller 120then stops transmitting the wireless power supplied for communication instep 502.

Referring to FIG. 4, the controller 120 determines whether the powertransmitting request message is received from the power receivingapparatus within the preset time in step 400.

When the power transmitting request message is received the controller120 determines whether the power can be transmitted to the powerreceiving apparatus in step 401. Specifically, the controller 120calculates the power value required by the power receiving apparatus 200by using the reference voltage value, the reference current value, andthe reference efficiency value included in the power transmissionrequest message. The controller 120 then determines whether the valuegenerated by adding the power value being transmitted by the powertransmitting apparatus and the calculated power value required by thepower receiving apparatus 200 is smaller than the maximum output powervalue of the power transmitting apparatus. If the value generated byadding the power value being transmitted by the power transmittingapparatus and the calculated power value required by the power receivingapparatus 200 is smaller than the maximum output power value of thepower transmitting apparatus, the controller 120 determines that thepower can be transmitted to the power receiving apparatus 200.

If the power transmission request message is not received in step 400,the controller 120 determines that there is no power receiving apparatusand stops transmitting the wireless power supplied for communication instep 502 of FIG. 5.

If the power can be transmitted in step 401, the controller 120transmits the power transmission approval message to the power receivingapparatus 200 in step 403. Thereafter, the controller 120 transmits therequested wireless power to the power receiving apparatus.

If the power cannot be transmitted in step 401, the controller 120transmits the power transmission rejection message to the powerreceiving apparatus in step 402. The controller 120 then stopstransmitting the wireless power supplied for communication in step 502of FIG. 5.

In step 404, the controller 120 determines whether the powertransmission state message is received from the power receivingapparatus within the preset time.

If the power transmission state message is received, the controller 120renews the power receiving apparatus management table by using thereceived power transmission state message in step 405. Specifically, thecontroller 120 renews the power receiving apparatus management tablestored in the memory by using the values of the reception voltage, thereception current, the output voltage, and the output current of thepower receiving apparatus contained in the power transmission statemessage.

If the power transmission state message is not received in step 404, thecontroller 120 determines that there is no power receiving apparatus andstops transmitting the wireless power supplied for communication in step502 of FIG. 5.

In step 406, the controller 120 calculates the transmission power value,which the power transmitting apparatus desires to transmit to the powerreceiving apparatus 200, by using the renewed power receiving apparatusmanagement table.

In step 407, the controller 120 calculates the leakage power value bycollecting information on the power receiving apparatus 200 existing inthe network. Specifically, the controller 120 calculates the leakagepower value using the values for the output current and the outputvoltage of the power receiving apparatus 200, the transmission powervalue, and the reference efficiency value of each power receivingapparatus, the values being received from the power receiving apparatus200. For example, when the transmission power value of the powertransmitting apparatus is 10 W and a total of power values receivedaccording to the reference efficiency value of each power receivingapparatus 200 is 8 W, the leakage power value is 2 W.

In step 408, the controller 120 determines whether the calculatedleakage power value is within the acceptable range. That is, if thecalculated leakage power value is within the preset threshold, thecontroller 120 determines that the leakage power value is within theacceptable range.

When the calculated leakage power value is within the acceptable range,the controller 120 transmits the calculated power transmission value tothe power receiving apparatus in step 409. The calculated powertransmission value is converted from the current transmission powervalue.

However, when the calculated leakage power value is not within theacceptable range, the detected power receiving apparatus is determinedas invalid materials in step 309 of FIG. 3.

In step 410, the controller 120 determines whether the powertransmission completion message is received from the power receivingapparatus.

When the power transmission completion message is not received, thecontroller 120 continuously determines whether the power transmissionstate message is received in step 404.

However, when the power transmission completion message is received, thecontroller 120 converts the transmission power value into the powervalue used for performing communication by the power receiving apparatus200 and then transmits the converted transmission power value in step411.

In step 500, the controller 120 determines whether the powertransmission standby state message is received.

When the power transmission standby state message is not received, thecontroller 120 stops transmitting the wireless power supplied forcommunication in step 502.

However, when the power transmission standby state message is receivedin step 500, the controller 120 determines whether the power can betransmitted to the power receiving apparatus in step 501.

When the power can be transmitted, s the power transmission approvalmessage is transmitted to the power receiving apparatus in step 403, andsteps 404 to 411 are subsequently performed.

However, if the power cannot be transmitted in step 501, the controller120 continuously determines whether the power transmission standby statemessage is received in step 500.

FIGS. 6 to 7 are flowcharts illustrating a process in which a powerreceiving apparatus performs wireless power transmission with a powertransmitting apparatus according to an embodiment of the presentinvention.

Referring to FIG. 6, the controller 210 detects power reception in step600. In step 601, the controller 210 generates a network subscriptionrequest message including the ID, the protocol version, and thereference load value of the power receiving apparatus for subscribing tothe wireless multi-power transmission network and then transmits thegenerated network subscription request message to the power transmittingapparatus.

In step 602, the controller 210 determines whether the networksubscription approval message is received from the power transmittingapparatus within the preset time.

If the network subscription approval message is received, the controller210 transmits the power transmission request message to the powertransmitting apparatus in step 603. However, if the network subscriptionapproval message is not received from the power transmitting apparatuswithin the preset time, the controller 210 retransmits the networksubscription request message to the power transmitting apparatus in step601. For example, when the network subscription approval message is notreceived from the power transmitting apparatus, it may mean that anetwork subscription rejection message is received or no approvalmessage is received.

In step 604, the controller 210 determines whether the powertransmission approval message is received from the power transmittingapparatus within the preset time.

If the power transmission approval message is received, the controller210 supplies power to the battery unit 250 by turning on the switch ofthe output terminal in step 605, and measures the reception voltage, thereception current, the output voltage, and the output current of theoutput terminal in step 606. In step 607, the controller 210 generatesthe power transmission state message including the measured outputvoltage, output current, reception voltage, and reception current, andthen transmits the generated power transmission state message to thepower transmitting apparatus.

In step 608, the controller 210 determines whether the power receptionis completed. If the power reception is not completed, steps 606 to 608are repeated. However, if the power reception is completed in step 608,the controller 210 stops supplying the power to the battery unit 250 byturning off the switch of the output terminal in step 609.

Referring to FIG. 7, in step 700, the controller 210 transmits thegenerated power transmission completion message to the powertransmitting apparatus.

If the power transmission approval message is not received within thepreset time in step 604, or after transmitting the generated powertransmission completion message to the power transmitting apparatus instep 700, the controller 210 supplies the power to the battery unit 250by turning on the switch of the output terminal in step 701 of FIG. 7.

The controller 210 measures the output voltage and the output current ofthe output terminal in step 702 and stops supplying the power to thebattery unit 250 in step 703.

In step 704, the controller 210 transmits the power transmission standbystate message including the measured output voltage and output currentto the power transmitting apparatus.

In step 705, the controller 210 determines whether the power receptionis completed. If the power reception is completed, the controller 210transmits the power transmission standby state message to the powertransmitting apparatus in step 704. Accordingly, the controller 210 canmaintain the communication connection with the power transmittingapparatus by periodically transmitting the power transmission standbystate message to the power transmitting apparatus.

However, if the power reception is not completed, the controller 210determines whether the power transmission approval message is receivedfrom the power transmitting apparatus in step 604 of FIG. 6. Thereafter,steps 605 to 609 are performed.

FIG. 8 is a diagram illustrating states of a power receiving apparatusaccording to an embodiment of the present invention.

Referring to FIG. 8, the power receiving apparatus enters a registrationstate 800 for the wireless power transmission performed with the powertransmitting apparatus. That is, the power receiving apparatus detectsthe power transmitted from the power transmitting apparatus, generatesthe network subscription request message including power transmissionstate information such as the ID, the protocol version, and thereference load value of the power receiving apparatus for thesubscription to the wireless multi-power transmission network, andtransmits the generated network subscription request message to thepower transmitting apparatus.

If a network subscription approval message is received from the powertransmitting apparatus, the power receiving apparatus enters a powertransmission determination state 810 for waiting for a powertransmission approval or a power transmission rejection from the powertransmitting apparatus. That is, the power receiving apparatus transmitsthe power transmitting request message for requesting the powertransmission to the power transmitting apparatus and waits to receivethe power transmission approval message or the power transmissionrejection message.

If the network subscription approval message is not received from thepower transmitting apparatus or the network subscription rejectionmessage is received from the power transmitting apparatus, the powerreceiving apparatus retransmits the network subscription request messageto the power transmitting apparatus and remains in the registrationstate 800.

If the power transmission approval message is received from the powertransmitting apparatus, the power receiving apparatus enters a powertransmission state 830 for performing the power transmission with thepower transmitting apparatus. That is, the power receiving apparatusreceives the wireless power from the power transmitting apparatus.

If the power transmission approval message is not received from thepower transmitting apparatus or the power transmission rejection messageis received from the power transmitting apparatus, the power receivingapparatus enters a power transmission standby state 820. That is, thepower receiving apparatus maintains communication without receiving thewireless power from the power transmitting apparatus. That is, the powerreceiving apparatus receives only power for the communication from thepower transmitting apparatus.

The power receiving apparatus measures the output voltage and the outputcurrent and transmits the power transmission standby state messagecontaining the measured output voltage and output current to the powertransmitting apparatus. Then, if the power reception is not completed,the power receiving apparatus enters the power transmissiondetermination state 810.

If the power receiving apparatus receives the power transmissionapproval message from the power transmitting apparatus in the powertransmission standby state 820, the power receiving apparatus enters thepower transmission state 830.

If the power reception is completed in the power transmission state 830,the power receiving apparatus enters a power transmission completionstate 840. That is, the power receiving apparatus determines that thepower transmission is completed and stops supplying the power to thebattery unit after turning off the switch of the output terminal.

The power receiving apparatus transmits the power transmissioncompletion message to the power transmitting apparatus in the powertransmission completion state 840 and enters the power transmissionstandby state 820. In the power transmission standby state 820, thepower receiving apparatus maintains the communication connection byperiodically transmitting the power transmission standby state messageto the power transmitting apparatus.

FIG. 9 illustrates an example of a power receiving apparatus managementtable according to an embodiment of the present invention.

Referring to FIG. 9, the power receiving apparatus management tableincludes fields for a Network ID, an ID, a reference load, a referencecurrent, a reference voltage, a reference efficiency, a state, an inputvoltage, an input current, an output voltage, an output current, atransmission order, and a priority of a power receiving apparatus, foreach power receiving apparatus managed in the table. Here, if the powerreceiving apparatus is located in the resonator of the powertransmitting apparatus, based on an assumption that the powertransmitting apparatus transmits prearranged regular power, thereference load refers to a value generated by quantizing a numericalvalue converted from the voltage or the current measured in theresonator of the power transmitting apparatus. Further, the referenceefficiency refers to a quantized ratio of power transmitted by the powertransmitting apparatus to power received by the power receivingapparatus when the power receiving apparatus receives sufficient powerfrom the power transmitting apparatus so that the power transmission isnormally performed. The reference voltage refers to a maximum voltage,which can be applied to the output terminal of the power receivingapparatus in an environment where the power receiving apparatus receivessufficient power from the power transmitting apparatus. The referencecurrent refers to a maximum current, which can be applied to the outputterminal of the power receiving apparatus in the environment where thepower receiving apparatus receives sufficient power from the powertransmitting apparatus. The transmission order refers to an order ofpower receiving apparatuses receiving power from the power transmittingapparatus, and the priority refers to an order preset between aplurality of power receiving apparatuses for the power reception.

For example, if a maximum transmission power value that can betransmitted by a power transmitting apparatus is 8 W and a transmissionpower value is 5 W, it is assumed that the controller 120 istransmitting a total of 4.2 W of power to power receiving apparatuseswith Network IDs of 2, 3, and 4 as illustrated in FIG. 9. Further, thefollowing description is based on an assumption that the powertransmitting apparatus can transmit the power to 5 power receivingapparatuses in one network.

When the power receiving apparatus with the network ID of 1 newlysubscribes to the network for the power transmission, if the powertransmission request message is received from the power receivingapparatus with the network ID of 1, the controller 120 calculates thepower value required by the power receiving apparatus using thereference voltage value, the reference current value, and the referenceefficiency value included in the received power transmission requestmessage. For example, when the reference current of the power receivingapparatus with the network ID of 1 is 300 mA, the reference voltage is 5V, and the reference efficiency is 75%, a power value which the powerreceiving apparatus with the network ID of 1 can receive is 1.125 V.That is, the power receiving apparatus can receive only power of 1.125 Veven though the power transmitting apparatus transmits power of 1.5 Vbased on the reference current and the reference voltage.

The controller 120 determines whether the value generated by adding thepower value being transmitted by the power transmitting apparatus andthe power value required by the power receiving apparatus is smallerthan the maximum output value of the power transmitting apparatus. Ifthe added value is smaller than the maximum output value, the controller120 can transmit the power to the power receiving apparatus with thenetwork ID of 1.

For example, when the power value being transmitted by the powertransmitting apparatus is 4.2 V, the power value required by the powerreceiving apparatus is 1.5 V, and the maximum output power value of thepower transmitting apparatus is 8 W, the controller 120 can transmit thepower to the power receiving apparatus with the network ID of 1 becausethe value generated by adding the value of 4.2 V and the value of 1.5 Vis smaller than 8 W.

Thereafter, the controller 120 transmits the power transmitting approvalmessage to the power receiving apparatus with the network ID of 1 andtransmits power of 1.5 V to the power receiving apparatus with thenetwork ID of 1.

When the power receiving apparatus with the network ID of 1 and thepower receiving apparatus with the network ID of 5 are newly subscribedto the network for the power transmission, if the power transmittingapparatus can transmit power to only one power receiving apparatus, thecontroller 230 can transmit the power to one power receiving apparatusdesired to first receive the power with reference to the predeterminedtransmission order and priority between the two power receivingapparatuses. In this case, a power receiving apparatus having notreceived the power enters the power transmission standby state andtransmits the power transmission standby state message to the powertransmitting apparatus. Thereafter, when the power transmission of thepower receiving apparatus currently receiving the power is completed,the power transmitting apparatus enables the power transmission to beperformed by transmitting the power transmission approval message to thepower receiving apparatus in the power transmission standby state.

For example, when the power receiving apparatus with the network ID of 5has a priority of 4, the controller 120 can transmit the powertransmission approval message to the power receiving apparatus with thenetwork ID of 5 after the power transmission of power receivingapparatuses with network IDs of 2, 3, and 4 is completed.

The power transmitting apparatus and method according to theabove-described embodiments of the present invention can stably transmitpower to each power receiving apparatus by considering powertransmission states of a plurality of power receiving apparatuses.

While the present invention has been particularly shown and describedwith reference to certain embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims and theirequivalents.

What is claimed is:
 1. A method for wireless power transmission by apower transmitting apparatus, the method comprising: transmittingdetection power; detecting an impedance change made by a power receivingapparatus; transmitting driving power for communication with the powerreceiving apparatus towards the power receiving apparatus; receiving,through a communication circuit, a search signal from the powerreceiving apparatus, the search signal including information regarding areference load impedance; comparing the impedance change with thereference load impedance; in response to a difference between theimpedance change and the reference load impedance being out of a firstacceptable range, transmitting, through the communication circuit, arejection message to the power receiving apparatus and stoppingtransmission of the driving power; and based on the difference betweenthe impedance change and the reference load impedance being within thefirst acceptable range: transmitting wireless power towards the powerreceiving apparatus; receiving information regarding the power receivingapparatus; identifying a leakage power value of the power receivingapparatus based on the information regarding the power receivingapparatus; determining whether the leakage power value of the powerreceiving apparatus is within a second acceptable range; and stoppingtransmission of the wireless power towards the power receiving apparatusbased on the leakage power value being out of the second acceptablerange.
 2. The method of claim 1, further comprising: in response to thedifference between the impedance change and the reference load impedancebeing within the first acceptable range, transmitting an approvalmessage to the power receiving apparatus.
 3. The method of claim 1,further comprising: storing a power management table including stateinformation for power transmission on at least one power receivingapparatus.
 4. The method of claim 3, wherein the state informationincludes an Identifier (ID), reference load, reference current,reference voltage, reference efficiency, power transmission state, inputvoltage, input current, output voltage, and output current of the powerreceiving apparatus.
 5. The method of claim 3, further comprising:receiving a state message from the power receiving apparatus; anddetermining a transmission power value using the stored power managementtable and the received state message.
 6. A power transmitting apparatusfor wireless power transmission, the power transmitting apparatuscomprising: a resonator; a communication unit; and a controllerconfigured to at least control to: transmit detection power through theresonator, detect an impedance change made by a power receivingapparatus, transmit driving power for communication with the powerreceiving apparatus, through the resonator, towards the power receivingapparatus, receive, through the communication circuit, a search signalfrom the power receiving apparatus, the search signal includinginformation regarding a reference load impedance, compare the impedancechange with the reference load impedance, in response to a differencebetween the impedance change and the reference load impedance being outof a first acceptable range, transmit, through the communicationcircuit, a rejection message to the power receiving apparatus and stoptransmission of the driving power, and based on the difference betweenthe impedance change and the reference load impedance being within thefirst acceptable range: transmit wireless power towards the powerreceiving apparatus, receive information regarding the power receivingapparatus. identify a leakage power value of the power receivingapparatus based on the information regarding the power receivingapparatus, determine whether the leakage power value of the powerreceiving apparatus is within a second acceptable range, and stoptransmission of the wireless power towards the power receiving apparatusbased on the leakage power value being out of the second acceptablerange.
 7. The power transmitting apparatus of claim 6, wherein thecontroller is further configured to control to, in response to thedifference between the impedance change and the reference load impedancebeing within the first acceptable range, transmit an approval messagetowards the power receiving apparatus.
 8. The power transmittingapparatus of claim 6, wherein the controller is further configured tocontrol to store a power management table including state informationfor power transmission on at least one power receiving apparatus.
 9. Thepower transmitting apparatus of claim 8, wherein the state informationincludes an Identifier (ID), reference load, reference current,reference voltage, reference efficiency, power transmission state, inputvoltage, input current, output voltage, and output current of the powerreceiving apparatus.
 10. The power transmitting apparatus of claim 9,wherein the controller is further configured to control to: receive astate message from the power receiving apparatus, and determine atransmission power value using the stored power management table and thestate message.